Just to be clear, I'm not trying to down play your emotions or the current situation. But rather offer the perspective that, if everything works out okay, which it should, this won't be the last time you feel this fear. The good news is feeling this fear is a GOOD thing. It shows how you really feel and what kind of father you will be.
Shit, I picked up my 15 year old son at the movies the other day, and the state of panic I was in because he was one of the last people to leave the theater was insane. All these thoughts and crazy Hollywood movie plots ran through my mind. When he finally walked out a clam rushed over and I felt great, like the couple seconds after an icecream headache fades... Wonderful